So this little wander started at the auction house. My first thought was "Fake," mostly because the decoration on the silver cap really reminds me of some of the funky folk jewelry that comes out of India. But they're starting the bids awfully high, which suggests somebody thinks they won't get sued for it. The description accompanying the piece isn't very helpful - they say it's "Viking," but not where it was found or on what basis they assigned the 9th-10th cen. dating. (A lot, but not all, of their "Viking" stuff is Baltic - I suspect those countries have less stringent export laws...)
Archive.org has the text they cite as a source. It's from 1897, which does not inspire me with great confidence.
These [flint arrowheads] they find in Scotland in much greater plenty, especially in the prefectury of Aberdeen, which, as the learned S^ Robert Sibbald^ informs us, they there call Elf- arrows — Lamiarum Sagittas — imagining they drop from the clouds, not being to be found upon a diligent search, but now and then by chance in the high beaten roads. (362)
Mention has already been made of the superstition attaching to flint arrow-heads in Scotland, where they were popularly regarded as the missiles of Elves. In speaking of them Dr. Stuart quotes Robert Gordon of Straloch, the well-known Scottish geographer, who wrote about 1661. After giving some details concerning elf- darts, this writer says that these wonderful stones are sometimes found in the fields and in public and beaten roads, but never by searching for them; to-day, perhaps one will be found where yesterday nothing could be seen, and in the afternoon in places where before noon there was none, and this most frequently under clear skies and on summer days. He then gives instances related to him by a man and a woman of credit, each of whom while riding found an arrow-head in their clothes in this unexpected way. Mr. F. C. Lukis, F.S.A./ draws a distinction between the elf-shot or elf -arrow and the elf-dart, the latter being of larger dimensions and leaf-shaped. He gives an engraving of one which has been mounted in a silver frame and worn as a charm. The cut is here reproduced, as Fig. 271. The initials at the back are probably those of the owner, who mounted the amulet in silver, and of his wife. It was worn by an old Scottish lady for half a century. Others thus mounted were exhibited in the Museum of the Archaeological Institute at Edinburgh in 1856.(364-365)
He goes on to speak of contemporary Irish and British superstitions regarding elf-arrows and elf-darts, all in similar veins. Nothing is earlier than the 1661 cite.
THere's the famous Old English charm Wið Faerstice, "Against a Stitch," (10th-11th cen) which is the super-duper evidence of Anglo-Saxon belief in elves and elf-shot; but if that translation is to be believed, the elf-spears are of iron, not stone. Also, it says nothing about using one as a talisman, but rather using the charm, together with herbs seethed in boiling butter, to cure the pain resulting from an attack.
This Archaeology article is the only thing I've turned up on a quick look for a possible arrowhead-talisman finding. The article is vague on dates - the monastery in question was founded in the 12th century, but I don't know if there's a date for the particular grave in/near which the arrowhead was found. Certainly, I don't recall seeing a stone arrowhead in any of the (not very many) Anglo-Saxon cemetary catalogues I've gone through.
For reference, this is a nice infographic showing the different sorts of stone arrowheads found in Great Britian.
I dug around in the closet where I found my old rock collection a month ago - sure enough, I still have a half-dozen flint arrowheads. One's triangular, and one's leaf-shaped if you squint at it.
Between the ammonite, the cowrie shells, the boar's tooth, and the arrowhead, I've got a nice collection of Anglo-Saxon talismans (or possible talismans) in the works. I should make a display out of them or something.